Current Employment Statistics Benchmark
In accordance with annual practice, the establishment survey data have been revised to reflect comprehensive universe counts of payroll jobs, or benchmarks. These counts are derived principally from unemployment insurance tax records compiled by the Quarterly Census of Employment and Wages [QCEW, http://www.bls.gov/cew/ ] program for March 2008. As a result of the benchmark process, all not seasonally adjusted data series were subject to revision from April 2007 forward, the time period since the last benchmark was established. In addition, with this release, the seasonally adjusted establishment survey data from January 2004 forward were subject to revision due to the introduction of updated seasonal adjustment factors.
The revised data for April 2008 forward incorporate the effect of applying the rate of change measured by the sample to the new benchmark level, as well as updated net business birth/death model adjustments and new seasonal adjustment factors. The November and December 2008 revisions also reflect the routine incorporation of additional sample receipts into the November final and December second preliminary estimates. The total nonfarm employment level for March 2008 was revised downward by 89,000 (17,000 on a seasonally adjusted basis). The previously published level for December 2008 was revised downward by 172,000 (311,000 on a seasonally adjusted basis). An article that discusses the benchmark and post-benchmark revisions, as well as all revised historical Current Employment Statistics (CES) data, can be accessed from the U.S. Bureau of Labor Statistics on the CES homepage at http://www.bls.gov/ces/.
Household Survey Adjustments
Effective with data for January 2009, updated population estimates have been used in the household survey. Population estimates for the household survey are developed by the U.S. Census Bureau [BOC, http://www.census.gov/ ]. Each year, the Census Bureau updates the estimates to reflect new information and assumptions about the growth of the population during the decade. The change in population reflected in the new estimates results primarily from adjustments for net international migration, updated vital statistics information, and some methodological changes in the estimation process.
In accordance with BLS's usual practice, they will not revise the official household survey estimates for December 2008 and earlier months. The adjustment decreased the estimated size of the civilian noninstitutional population in December by 483,000, the civilian labor force by 449,000, and employment by 407,000; the new population estimates had a negligible impact on unemployment rates and other percentage estimates. Data users are cautioned that these annual population adjustments affect the comparability of household data series over time. Estimates of large levels, such as total labor force and employment are impacted most. More detailed information on the population adjustments and their effect on national labor force estimates are available at http://www.bls.gov/cps/cps09adj.pdf.